Wideband Omnidirectional Antenna Featuring Small Azimuthal Gain Variation.

Area of Science:

• Electrical Engineering
• Antenna Theory
• Electromagnetics

Background:

• Wideband omnidirectional antennas are crucial for radio monitoring and communication systems.
• Achieving consistent gain across all directions over a wide bandwidth is a significant challenge.
• Existing designs often struggle with gain variation and compact size.

Purpose of the Study:

• To present a novel wideband omnidirectional antenna design.
• To achieve a 1-dB gain variation across the azimuthal plane from 1.8 GHz to 7.77 GHz.
• To enhance impedance bandwidth and reduce side lobe levels in a compact form factor.

Main Methods:

• Design utilizes two flower-bud-shaped monopoles for pattern superposition.
• A circular ground plane is employed to minimize azimuthal gain variation.
• An embedded matching structure, analyzed as a five-order LC circuit, broadens impedance bandwidth.
• Structural modifications are implemented to reduce side lobe levels.

Main Results:

• The antenna achieves a 1-dB gain variation across its azimuthal plane from 1.8 GHz to 7.77 GHz.
• Experimental measurements confirm an omnidirectional radiation pattern.
• S11 is below -10 dB from 1.8 GHz to 7.7 GHz, indicating excellent impedance matching.
• Side lobe levels are effectively reduced through structural modifications.

Conclusions:

• The novel antenna design successfully meets the requirements for wideband omnidirectional performance with minimal gain variation.
• Its performance characteristics make it suitable for applications in mobile communications (LTE, Bluetooth, IEEE 802.11be) and radiolocation.
• The antenna is a promising candidate for unmanned aerial vehicles (UAVs) in communication and radio monitoring missions.